Ultrasonic transducers are used for generating and transmitting wave energy of a predetermined frequency to a liquid contained in a container. See, for example, U.S. Pat. No. 3,575,383 entitled ULTRASONIC CLEANING SYSTEM, APPARATUS AND METHOD THEREFOR. Transducers of this type can be used, for example, in ultrasonic cleaning equipment. The transducer is typically mounted to the side or the underside of a container which holds liquid, or mounted in a sealed enclosure which is immersed in a liquid in a container made of metal, plastic or glass. A single transducer or a plurality of transducers are then used to energize the liquid with sonic energy. Once energized with the sonic energy, the liquid achieves cavitation.
This type of transducer is also referred to as a "sandwich"-type transducer because it has one or more crystals sandwiched between a head mass (or front driver) and the tail mass (or rear driver). A sandwich-type of transducer is used in applications such as plastic welding, wire bonding, cataract and other medical surgical devices, among others.
Currently, some of the transducer elements are made from metallic materials including stainless steel, aluminum and titanium. Applicant has proposed using an additional element, called a resonator, to enhance the output of the transducer relative to conventional transducers, as disclosed in co-pending application Ser. Nos. 08/644,843, and 08/792,568. In one embodiment, ceramic material is identified as a preferred material for the resonator element.
It has now been discovered, however, that even greater advantages can be obtained where ceramic materials are substituted for the metal components of a transducer and/or other structures used to generate and transmit ultrasonic energy.